import 'package:flutter/material.dart';
import 'package:english_words/english_words.dart';

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      theme: new ThemeData(
        primaryColor: Colors.black,
      ),
      home: new RandomWords(),
    );
  }
}

class RandomWords extends StatefulWidget {
  @override
  createState() => new RandomWordsState();
}

class RandomWordsState extends State<RandomWords> {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('Startup Name '),
        actions: <Widget>[
          new IconButton(icon: new Icon(Icons.list), onPressed: _pushSaved),
        ],
      ),
      body: _buildSuggestions(),
    );
  }

  void _pushSaved() {
    Navigator.of(context).push(
      new MaterialPageRoute(
        builder: (context) {
          final tiles = _saved.map(
            (pair) {
              return new Container(
                color:Colors.black87,
                padding: const EdgeInsets.all(0),
                child:new ListTile(
                  title: new Text(
                    pair.asPascalCase,
                    style: TextStyle(color: Colors.white),
                  ),
                )
              );
            },
          );

          final divided = ListTile.divideTiles(
            context: context,
            tiles: tiles,
          ).toList();

          return new Scaffold(
            appBar: new AppBar(
              title: new Text('Saved Suggestions'),
            ),
            body: new ListView(children: divided),
          );
        },
      ),
    );
  }

  final _suggestions = <WordPair>[];

  final _saved = new Set<WordPair>();

  final _biggerFont = const TextStyle(fontSize: 18.0);

  Widget _buildSuggestions() {
    return new ListView.builder(

//        padding: const EdgeInsets.all(16.0),
        // 对于每个建议的单词对都会调用一次itemBuilder，然后将单词对添加到ListTile行中
        // 在偶数行，该函数会为单词对添加一个ListTile row.
        // 在奇数行，该函数会添加一个分割线widget，来分隔相邻的词对。
        // 注意，在小屏幕上，分割线看起来可能比较吃力。
        itemBuilder: (BuildContext context, int i) {
          // 在每一列之前，添加一个1像素高的分隔线widget
          if (i.isOdd) return new Divider(
              height:1.0
          );
          // 语法 "i ~/ 2" 表示i除以2，但返回值是整形（向下取整），比如i为：1, 2, 3, 4, 5
          // 时，结果为0, 1, 1, 2, 2， 这可以计算出ListView中减去分隔线后的实际单词对数量
          final index = i ~/ 2;
          // 如果是建议列表中最后一个单词对
          if (index >= _suggestions.length) {
            // ...接着再生成10个单词对，然后添加到建议列表
            _suggestions.addAll(generateWordPairs().take(10));
          }
          return _buildRow(_suggestions[index]);
        });
  }

  Widget _buildRow(WordPair pair) {
    final alreadySaved = _saved.contains(pair);
    return new Container(
        color:Colors.black87,
        padding: const EdgeInsets.all(0),
        child:new ListTile(
          title: new Text(
            pair.asPascalCase,
            style: TextStyle(color: Colors.white),
          ),
          trailing: new Icon(
            alreadySaved ? Icons.favorite : Icons.favorite_border,
            color: alreadySaved ? Colors.red : Colors.white,
          ),
          onTap: () {
            setState(() {
              alreadySaved ? _saved.remove(pair) : _saved.add(pair);
            });
          },
        )
    );
  }
}
